Hanau-Seligenstadt Valley
The Hanau-Seligenstädter Senke ( natural area 232.2) is a marginal basin of the Upper Rhine Rift in the area of the eastern Lower Main Plain (main unit 232), which is also known synonymously as the Eastern Lower Main Plane .
location
The Hanau-Seligenstädter Senke lies in the area of the eastern Lower Main Plain. The river Main flows through it between Aschaffenburg and Offenbach am Main . Due to its location in the eastern Rhine-Main area , the Hanau-Seligenstädter Senke is densely populated. The largest cities include Hanau , Seligenstadt and Dieburg .
Geological structure
The Hanau-Seligenstädter Senke is a Cenozoic , trench-like basin. As the edge basin of the Upper Rhine Rift , it belongs to the European Cenozoic Rift System , a fracture zone that runs through Europe from the North Sea to the Mediterranean.
In the west a horst ( Sprendlinger Horst , in the northern extension Frankfurter Horst ) separates the Hanau-Seligenstädter Senke from the Upper Rhine Graben. The eastern shoulder of the trench is formed by the Spessart . In the south, the valley is bounded by the Odenwald . In the north the shoulders of the trench converge like a wedge. The subsoil under the basin deposits is built up by the Variscan basement of the Central German Crystalline Zone and the discordant layer sequence from the Permian (Upper Rotliegend ) to the Lower Triassic ( Buntsandstein ). The layers deposited in the basin are more than 280 m thick and range from the Oligocene to the Quaternary . In the Oligocene and Miocene, marine, brackish and limnic , most recently continental clays , marls , limestone banks and sands with embedded basalt lavas predominate. The river deposits of the Pliocene and Quaternary consist of sand, gravel , silt and clay , in the Pliocene also lignite . The surface is shaped by a river terrace landscape.
History of origin
From the Triassic to the early Paleogene , the area of today's Hanau-Seligenstädter Senke was not a deposit area, but an area of erosion. The subsidence began at the latest in the Oligocene ( Rupelian ) around 30 million years ago during the formation of the Upper Rhine Rift. The Oberrheingrabenmeer or the Oberrheingrabenensee also extended over the area of the Hanau-Seligenstädter Depression. Debris carried in from the basin edges increasingly led to silting up of the lake in the course of the Miocene . The Hanau-Seligenstädter Senke became a river plain. Around 15 million years ago during the Langhium, volcanoes poured lava flows over parts of the area that have been preserved as solidified basalt rock . Even during the Langhian, the rivers began to remove their own deposits. It was not until the Pliocene (around 5 million years ago) that the Lower Main and its tributaries began to deposit sand , gravel and clay in their valleys . Layers of clay and peat (now brown coal ) formed in lakes and bogs . The then still relatively short Main tapped the Obermain in the early Quaternary . The resulting strongly increased river transported large quantities of sand and gravel into the Hanau-Seligenstädter valley. In the mid- Pleistocene , the rivers eventually began to dig into their older deposits again. The various stages of this burial history are preserved today in the form of river terraces .
Raw materials and groundwater
In the Hanau-Seligenstädter Senke sand, gravel and clay are extracted from numerous pits and quarry ponds. Pliocene lignite was mined in the region around Großkrotzenburg , Kahl am Main and Seligenstadt until the 1930s . Today the opencast mines form the Kahler Seenplatte . In the vicinity of Hanau, some disused quarries (e.g. the Dietesheim quarries ) testify to the extraction of Miocene basalts up to the 1980s. The sands and gravels are abundant aquifers that are used for the water supply.
Individual evidence
- ↑ Environmental Atlas Hesse: Map and Description
See also
swell
- Peter Prinz-Grimm and Ingeborg Grimm: Wetterau and Mainebene. Borntraeger, Berlin / Stuttgart 2002, ISBN 3-443-15076-4 ( collection of geological guides 93 ), esp.p. 8f.
- Stefan Lang: The geological development of the Hanau-Seligenstädter Senke (Hessen, Bavaria). Electronic publications Darmstadt (EPDA), 782, 97 pp., 51 fig., 5 tab., Appendix, 2007. [1]